‘This is going to be awesome,” exclaims the guy behind me in line as we wait for our turn on the Wooly Mammoth, a massive raft ride that whips riders down one of the largest serpentine tubes in the world. “For the last two days, I’ve been more excited than the kids.”

His daughter, a little slip of a thing, looks more than a little embarrassed by her father’s enthusiasm.

We’re checking out the recently opened Great Wolf Lodge in Niagara Falls, with its 100,000 square feet of sliding, spraying and splashing fun. From its ubiquitous lazy river, which gently floats people along slow, meandering currents, to the 13 colour-coded waterslides — including one that can only be described as a “water coaster” — the lodge is an example of one of the hottest trends in hotel and resort attractions: the multimillion-dollar indoor aquatic playground.

“We are weatherproof,” says Keith Simmonds, the resort’s general manager, who was here opening day in mid-April. “We are 84 degrees, 365 days of the year.”

The year-round advantage is catching on. At the beginning of 2000, there were only 18 hotel water-park resorts in North America, mostly in the Wisconsin Dells area, where cold, blustery weather pushes water sports for families wanting a weekend getaway. By the end of 2006, there should be at least 140 across North America.

Even economy and mid-level hotels, such as Holiday Inn and Best Western, are installing new water parks, albeit smaller than those found in mega-resorts.

Of course, building and maintaining a water park is expensive. Bill Haralson, a partner with Texas-based Hotel Waterpark Resort Research & Consulting, says it costs $338 to $450 a square foot to develop an indoor water park, including construction, furniture, theme decorations and play equipment. And once the doors open, it costs about $56 a square foot each year to operate. The yearly price tag for a 50,000-square-foot water park comes in at about $2.8-million.

Still, hotels and resorts are willing to dive in. And here’s why: On-site parks that paying hotel guests use for free not only help increase occupancy during the hard-to-fill slow seasons, but by installing an on-site water park, hotels can boost room rates by as much as $40 a person per night. Great Wolf Lodge rooms, for example, run a cool $354 to $584 for a night’s stay, depending on whether you opt for a no-frills bed-and-sofa suite, a fireplace loft suite, or something in between. But don’t expect room service, plates to use in the microwave or even more than one bar of soap.

“It’s all relative,” Haralson says. “It costs you more to build. It costs you more to operate, but your occupancy rates are higher and your room rates are drastically higher. You really hit the home runs with increased room rates.”

If you’re looking for some sliding, sloshing excitement, you have a glut of brand-spanking-new options to choose from:

Great Wolf Lodge

Niagara Falls, Ont.

The waterpark at the first Great Wolf Lodge in Canada is pretty darn big, although the granddaddy of them all, the World Waterpark at the West Edmonton Mall, still ranks biggest in North America at 200,000 square feet.

At Great Wolf, tiny kidlets splash around the zero-entry pool or whiz down a baby-sized tube slide. Big kids and adults check out a four-storey tree house water fort, the 450,000-litre wave pool or the Rocket Watercoaster, which uses water jets and conveyer belts to whip riders along. The park is exclusive to guests, so the queues stay short.

Fallsview Indoor Waterpark

Niagara Falls, Ont.

Canadian Niagara Hotels, which operates Sheraton at the Falls, the Brock Plaza Hotel, and the Skyline Inn, opened the complex in May for its guests. All three hotels are connected to the aquatic complex by indoor walkways.

Hampton Inn guests across the street can also use the waterpark. Try Toob Tower, The Plunge Bowl and Extreme Slide Racing. The names say it all.

Canadian Niagara Hotels: 1-800-263-7135; fallsviewwaterpark.com. Rooms from $199. Day passes for non-hotel guests cost $44.95; children 2 and under are free.

Plunge!

Collingwood, Ont.

Nestled at the base of Blue Mountain in the heart of the ski resort village, this 10,000-square-foot, indoor-outdoor facility is small by waterpark standards, but packs some punch, especially for preschoolers. Its outdoor heated pool stays open in even the worst weather (have fun watching the diehards run through sleet and snow to slither down the tube slide), but the indoor portion stays toasty.

Plunge!: 220 Mountain Dr., Collingwood, Ont.; 1-866-716-8102/ Prices: A Westin Trillium House family fun package from $295.45 this winter. Day rates are $42 for a family pass, $17 for an adult and $14 for a child.

Schlitterbahn

Galveston Island, Tex.

Its sister waterpark in New Braunfels, Tex., was named best waterpark in the U.S. by the Travel Channel in 2005. So what are they doing to top it in Galveston? Think two uphill water coasters, a surf ride, two family raft rides and three rivers. Phase three will introduce a saltwater pool stocked with fish for snorkelling. The Schlitterbahn parks prove you don’t have to build in a cold-weather state or province to draw crowds.

Kalahari Resort

Sandusky, Ohio

Surprisingly, three Wisconsin Dells resort owners, who have been competitors for decades, own this resort. With their rivalry put aside, at least in Ohio, they opened an African-themed resort last year complete with rental cabanas and a water coaster that whips riders around at about 40 kilometres an hour.

CORRECTION

Pricing for stays at Six Flags Great Escape Lodge & Indoor Waterpark in Queensbury, N.Y., starts at about $199 a night. An incorrect amount was listed in the Oct. 21 Travel section. For more information, call 1-888-708-2684 or visit sixflagsgreatescapelodge.com.